Starving Revenant and Lyla trigger for each card drawn.
Resolve all Starving Revenant triggers, causing you to gain 1 life and target opponent to lose 1 life for each trigger.
Resolve the first Lyla trigger, putting a +1/+1 counter on Fetid Gargantua.
Fetid Gargantua triggers, causing you to draw two cards and lose 2 life.
Repeat from step 2.
This clever loop relies on a self-sustaining chain of triggers that turns a single card draw into an infinite engine. Once you draw a card, Lyla, Holographic Assistant targets Fetid Gargantua with a +1/+1 counter, which in turn triggers Fetid Gargantua's ability to draw two more cards and keep the cycle going. Meanwhile, Starving Revenant sits on the board to capitalize on all that card draw once you have eight or more permanent cards in your graveyard, draining your opponent's life total while padding your own.